Circuit interrupter with movable tubular contact as sole vent for interrupting chamber



Oct. 27, 1964 R. G. COLCLASER, JR.. ETAL 3,154,658 CIRCUIT INTERRUPTER WITH MOVABLE TUBULAR CONTACT AS SOLE VENT FOR INTERRUPTING CHAMBER Filed 001:. 7, 1960 4 Sheets-Sheet 1 9. w to M Maw I0 .2 w M q- .1

ID NI WITNESSES: INVENTORS Robert G. Colclusendr 8 Russell N. Yeckley.

BY g m AT'ITORNEY R. G. COLCLASER, JR. ETAL 3,154,558 CIRCUIT INTERRUPTER WITH MOVABLE TUBULAR CONTACT TERRUPTING CHAMBER 4 Sheets-Sheet 2 NM NM Oct. 27, 1964 AS SOLE VENT FOR IN Flled Oct '7, 1960 R. e. COLCLASER, JR.. ETAL 58 CONTACT Oct. 27, 1964 CIRCUIT INTERRUPTER WITH MOVABLE TUBULAR AS SOLE VENT FOR INTERRUPTING CHAMBER 4 Sheets-Sheet 3 Filed Oct. 7, 1960 m 91 I I. 3

mm 5 M Mm E -ll ll l i 5 %w B mm mm x mm 5 N. l

mm a 2. Q

1964 R. G. COLCLASER, JR. ETAL 3,154,658

CIRCUIT INTERRUPTER WITH MOVABLE TUBULAR CONTACT AS SOLE VENT FOR INTERRUPTING CHAMBER Filed Oct. 7, 1960 4 Sheets-Sheet 4 ARC VOLTAGE E PUFFER-TYPE BREAKER ARC VOLTAGE E o|| CIRCUIT BREAKER Fig. 7.

76 1 0 ARC VOLTAGE J] INTERRUPTER OF THE INVENTION PAIR-BLAST BREAKER I CONTACT PART United States Patent CERCUET WETH Mtl-VAELE TUii'U- LAlR QTQNTACT A SQLE VENT FQR ENTER- RUPTHNG QHAMBER Robert G. Colclaser, in, and Russell N. Yecldey, Monroeviiie, Pa, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pan, a corporation of Pennsylvania Filed Get. '7, W60, Ser. No. 61,284 110 (Ilairns. ((Il. Zildldtl) This invention relates to circuit intcrrupters in general and, more particularly, to improved arc-extinguishing structures therefor.

A general object of the present invention is to provide an improved circuit interrupter which will be highly effective to extinguish currents over the entire current range with very short times, and at relatively high rates of rise of recovery voltage.

A more specific object of the present invention is to provide an improved arc-extinguishing unit in which improved gas-fiow conditions are encountered for highly effective arc interruption, while maintining the arc voltage at a relatively low value during the major portion of the half-cycle wave.

Another object of the present invention is to provide an improved circuit-interrupting unit in which are extinction is rapidly achieved and in which are erosion is maintained at a minimum value.

Still a further object of the present invention is to provide an improved arc-extinguishing unit in which gas flow for interrupting purposes is permitted to take place immediately upon contact separation without any obstruction thereto.

Many prior-art forms of compressed-gas circuit interrupters have utilized an interrupting chamber in which the movable contact has served as a plug, or stop for blocking gas flow through the orifice of said interrupting chamber until after the movable contact has passed theretbrough during the opening operation. It has been discovered that extremely highly eiiective interrupting conditions are obtained when the movable contact itself assumes the form of a hollow tube, and when gas flow is permitted to occur therethrough prior to withdrawal of the movable contact out of the opening provided by the interrupting chamber. It is, therefore, a distinct purpose of the present invention to provide for immediate flow of the arc-extinguishing gas during a circuit-interrupting operation and to cause the movable contact itself, which is of tubular form, to serve directly as the orifice, permitting thereby the interrupting chamber to merely provide essentially a gas-directing function.

Still a further object of the present invention is the provision of an improved relatively stationary contact structure, preferably of the contact finger type, in which an eccentric, or oil-center arcing horn is provided interiorly of the finger cluster constituting the relatively stationary contact finger assembly.

Yet a further object of the present invention is to provide an improved arc-extinguishing unit in which breakdown between the separated contact structure in the open circuit position is prevented by a novel shielding structure, which prevents corona from forming at relatively sharp corners of the contact structure.

An additional object of the present invention is the provision of an improved arc-interrupting unit particularly adapted for a double or dual-pressure type of circuit-interrupting structure in which the gas flow is so directed toward the established arc as to provide both a cross-blast action and also an axial-blast action. As well known by those skilled in the art, generally a cross-blast type of circuit interrupter is particularly effective for interrupting high-value currents at moderate voltage but because of 3,l5i,ti58 Patented Get. as, tees insulation ditficulties, an axial-flow type of circuit interrupter is usually used when interrupting high-voltage circuits.

It is, accordingly, an additional purpose of the present invention to combine both the features of the cross-blast and the axial-flow types of interrupters into a single unitary type of interrupting structure, which is highly effective during the interrupting of circuits of relatively high rates of rise of the recovery voltage transient at high current and voltage.

An ancillary object of the present invention is the provision of an improved arc-interrupting unit of the foregoing type, which is adaptable for use in a multi-break type of circuit-interrupting assemblage, in which the interrupting units may be repeated for the interruption of high-voltage transmission circuits. By such an arrange ment, the task or" interrupting the high-voltage high-power circuit may be divided between the several units, so that the voltage impressed upon each unit will be proportionately reduced. it is, however, obvious that for a multi-break arc-extinguishing assemblage it is desirable to provide an interrupting unit, which is adaptable for use, and may be readily positioned into place, with several other like units, and the entire arrangement being suitable for utilization with a multi-contact consruction.

Further objects and advantages will readily become apparent upon reading toe tollowin specification, taken in conjunction with the drawings, in which:

FIGURE 1 is a perspective view of a three-pole, highpower circuit interrupter suitable for controlling the three phases of a transmission system, and illustrating an embodiment of the present invention;

FIGURE 2 is a longitudinal vertical-sectional view taken through one of the grounded tank structures of FIG. 1 illustrating the arc-extinguishing assemblage in side elevation, and showing the disposition of the contact structure in the closed-circuit position thereof;

PEG. 3 is an enlarged, vertical-sectional view taken longitudinally throu h one of the several arc-extinguishing units of th multi-break arc-extinguishing assemblage of FIG. 2, the contact structure being illustrated in the closed-circuit position;

FZGURE 4 is a fragmentary view, similar to that of FIG. 3, but illustrating tne disposition of the several parts at an intermediate point during the opening operation of the interrupter;

PlGUitE 5 is a sectional top plan View taken substantially along the line VV of FIG. 4, but illustrating the disposition of the several contact parts in the fully opencircuit position of the interrupter;

FIGURE 5A illustrates, to a reduced scale one or" the several cross-arms supporting a movable contact, disassociated from the other cooperable structure; and,

FIGS. 69 illustrate oscillographic test results of arc and recovery voltages for various types of circuit-interrupting structures, P16. 8 illustrating the improved arcvoltage performance of the circuit interrupter of the present invention.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a three-pole high-voltage, high-power circuit interrupter suitable for controlling the three phases of a transmission system. Pole-unit A controls the lines L and L pole-unit B controls the transmission line L L and pole-unit C controls the current phase passing through line L L As shown, the circuit interrupter ll comprises a plurality of generally horizontally-extending grounded metallic tank structures 2 having end covers 3 associated therewith. The end covers 3 may be rotated about vertical hinge pins, not shown, to permit inspection into the interior of the tank structures 2 and withdrawal of the arena-e arc-extinguishing assemblage 4 (FIG. 2) laterally out of the tank structure 2 when such a maintenance operation is desired.

Disposed at opposite ends of the several tank structures 2, and extending upwardly therefrom, are supporting cylinders 5 having flanged apertured upper support plates 6, the latter serving to rigidly support into position entrance-type terminal-bushing structures 7. As well known by those skilled in the art, the terminal bushings 7 serve the function of passing the current to be interrupted into the interior of the tank structures 2. In addition, as more clearly shown in FIG. 2, the lower ends 8 of the terminal bushings 7 serve to support the arc-extinguishing assemblage 4, in bridging relation therewith, in a relatively fixed position.

Disposed below each of the horizontally-extending elongated tank structures 2 are auxiliary high-pressure storage tanks 11, which cooperate with the high-pressure reservoir chamber 11A (FIG. 2) which is disposed at the right-hand end of each of the several arc-extinguishing assemblages 4, as more clearly shown in FIG. 2. A mechanism housing 12 is provided which encloses the gas-control equipment and a suitable compressor, not shown, which is employed to extract relatively low-pressure gas from the interior 13 of the several tank structures 2 and to recompress it, forcing the recompresscd gas back, by a suitable pipe line, not shown, to the auxiliary high-pressure reservoir 11 and MA. A high-pressure connecting tube 14 (FIG. 2) interconnects the high-pressure reservoir 11 with the high-pressure reservoir 11A, which constitutes the right-hand extremity of each arcextinguishing assemblage 4, as more clearly shown in FIG. 2.

Disposed interiorly within the mechanism housing 12 is a suitable operating mechanism, for example one of the pneumatic type, which functions, by a suitable linkage, to effect reciprocal motion of an operating shaft, not shown, disposed interiorly within an operating tube 15 (FIG. 1) which interconnects the several pole-units A, B and C.

Encircling each of the terminal bushings 7 are current transformers 16, which serve to measure the current flow through the circuit interrupter l and also serve thereby to operate protective relaying equipment. Conduits 17 serve to carry the secondary leads of the current transformers 16 interiorly within the mechanism housing 12, in which a trip mechanism may be positioned.

With reference to FIG. 2, it will be observed that the arc-extinguishing assemblage 4 includes a rigid framework maintained in fixed position by insulating support bars 18, which are bolted, as at 19, 20 to support cast ings 21, 22. The support castings 21, 22 are fixedly secured to the lower ends 8 of the terminal bushings 7. As shown, the high-pressure reservoir chamber 11A is bolted to the right-hand support bracket 22 of the arc-extinguishing assemblage 4.

Associated with the high-pressure reservoir chamber 11A is a blast valve 23 (FIG. 3) biased to the closed position by a compression spring 24, and opened by a pilot-valve assembly 27 (FIG. 2) as set out more in detail in United States patent application filed January 23, 1959, Serial No. 788,668, now US. Patent 3,157,983, issued October 9, 1962 to Russell N. Yeckley, Joseph Sucha and Benjamin P. Baker, and assigned to the assignee of the instant application. The blast valve 23 is operated by a pneumatic valve piston, not shown, which,

in turn, is operated by the pilot-valve assemlby 27 (FIG. 2) operated by a main operating lever 28, pivotally mounted at 29. The main operating lever 28 has a pair of thrust-links 31 (only one being shown in FIG. 1) pivotally secured thereto, as at 32. The left-hand ends or" the two thrust-links 31, as viewed in FIG. 2, are pivotally connected to the right-hand ends of the two spaced movable operating rods 33 (FIG. 1), which move in a reciprocal manner, back and forth, during the opening and closing operations, as viewed in FIGS. 1 and 2.

Interconnecting the left-hand ends of the two spaced insulating operating rods 33, as viewed in FIG. 1, is a bridging spring-plate 34, which is biased toward the left by a compression spring 35. At the end of the opening operation, the spring-plate 34 strikes a bumper stop 36 and is arrested thereby bringing the entire movable contact assemblage to a cushioned stop.

Spaced axially along the insulating operating rods 33, and bridging the two operating rods 33, are a plurality of movable contact cross-arms 37 (FIG. 5A). The crossarms 37, are pivotally pinned to the two spaced insulating operating rods 33, and form a generally movable ladderlike contact assemblage 39. Disposed at the center of each cross-arm 37 is pinned, by a guide pin 38, an extension 41 of a tubular movable slotted contact 42. As shown in FIG. 3, each movable tubular contact tube 42 has elongated slots 43 provided longitudinally therein. In addition, each movable contact tube 42 functions as an orifice during the opening operation of the interrupter, and maintains a relatively tight fit with an inwardly extending orifice portion 44 of a cup-shaped tubular member 45, which, in effect, constitutes an interrupting chamber 46. The tubular member 45 is preferably formed of a suitable high-temperature material, such as polytetrafiuoroethylene.

As more clearly shown in FIGS. 3 and 4, the insulating tubular member 45 is clamped, by an annular clamping ring 47, to the bracket 22, the latter having suitable gasfiow passages provided therein, as shown. Bolts 4-8 fixedly secure the clamping ring 47 over a flanged end 51 of the interrupting member 45.

Disposed at the right-hand end of the interrupting chamber as, defined by the tubular member 45, is a relatively-stationary finger cluster 53 comprising a pinrality of relatively stationary finger contacts 54. As shown, the contacting portions 55 of the finger contacts 54 bear radially inwardly from the outer side wall 56 of the tubular orifice contact 42. Moreover, an eccentrically-located arcing born 57 is provided, having an arc-resisting tip-portion 58. The arc-resisting tip-portion 58 may be formed of a suitable arc-resisting material, such as a silver-tungsten alloy. By locating the arcing horn 57 off-center, or eccentric with respect to the centerline 61 of the interrupting unit 62., the are as (FIG. 4), initially drawn between the movable contact 42 and the finger-portions 55 of the stationary fingers 54, is more quickly transferred thereto during the opening operation of the interrupter ll.

Disposed externally of the tubular member 45, constituting the interrupting chamber 46, is a cylindrical blast-tube member 64 composed of a suitable arc-resisting insulating material. The blast tube 64 serves the function of preventing the gas blast from striking component parts of the interrupting assemblage 4 directly, and, in addition, somewhat aifects their cooling prior to final exhausting into the interior 13 of the tank structure 2.

As indicated in FIGS. 2 and 3, each arc-extinguishingunit 62 is provided with a gas-inlet opening. The interrupting unit as, which is nearest the reservoir 11A, is providde with only a short blast-passage 65, the latter being formed as an integral part of the support casting 22. Additional blast tubes 66 serve to transmit a flow of high-pressure gas from the high pressure reservoir MA to the adjacently-positioned interrupting units 62, so that upon initial contact separation a flow of highpressure gas will be present within each unit 62.

To assist in guiding the opening and closing movement of each tubular movable contact 42, a stationary guide cylinder 67 is provided. Preferably this guide cylinder 67 is slotted, as at 68, to provide a cluster of relatively stationary contact fingers 69, which bear upon the external surface 56 of the tubular movable contact 4-2. An electrostatic sleeve 70, bolted to the guide cylinder d7, encompasses the several stationary contact fingers 69 to prevent corona forming thereat in the fully open-circuit position of the interrupter 1. A polytetrafluoroethylene guide-ring 71 is employed, in conjunction with the electrostatic sleeve 70, to assist in guiding the opening and closing motions of the tubular movable contact 42. As well known by those skilled in the art, the polytetrafluoroethylene guide ring 71 has a very low coefficient of friction. As a result of the aforesaid construction, the relatively stationary contact fingers as. associated with he slotted guide tube 67, are completely covered and, as a result, no corona formation, and consequent breakdown between the separated contacts in the open-circuit position, is permitted.

As shown in FIGURE 3, the slotted tubular guide sleeve 67 of one interrupting unit 62 may constitute a portion of the relatively stationary cont-act structure 52 for the immediately adjacently-disposed interrupting unit The opening operation of the circuit interrupter 1 will now be described. As pointed out previously, during the opening operation the operating mechanism, not shown, disposed interiorly within the mechanism housing 12. will be tripped by suitable means, not shown, and the several accelerating springs, including the comp-ression springs 35, will effect simultaneous opening of all the movable contact structures 35? at one time. Additionally, the release of the operating rod 73 and the leftward opening movement of the movable contact structure 39 will eifect operation of the pilot-valve assembly 27, as set forth in the aforesaid patent application by Yeckley, Sucha and Baker. This will open the blast valve 23 to permit thereby a flow of high-pressure gas, say at a pressure of 220 p.s.i., to flow through the blast inlet opening as in the direction as indicated by the arrow 74 in FIG. 4. This flow of gas will take place through the tubular contact 42 even before contact separation takes place. As a result, the are 63 is initially drawn in an axial flow of high-pressure gas.

Due to the off-center positioning of the arc horn 57, which results in its close proximity to the lower side Wall 75 of movable contact 42, as viewed in FIG. 3, the arc will quickly transfer from the contacts &2, 55 to the tip portion 5% of the arcing horn 57 and the inner wall 75 of movable tubular contact 42. During the peak of the current wave, that is during relatively high instantaneous values of arcing current, the arc us will terminate close to the mouth 72 of movable tubular contact 42. The are as will be moved down the inner side wall 75' of the movable orifice contact 42 during relatively low instantaneous values of arcing current because of the cross-blast action. Near a current zero on the descending portion of the alternating-current wave the are 63 will lengthen along the inner side wall 75 of each movable orifice contact as, and will cause a sharp peak of arc voltage, as indicated at the point '76 in FIG. 8 of the drawings. As a result, during the major portion of the half cycle of current flow, the arc voltage is maintained at a relatively low value, and it is only near the current zero portion of the current wave that a relatively sharp peak of arc voltage is encountered. This is highly desirable, inasmuch as it results in a relatively low energy loss within the circuit interrupter 1 during an opening operation. This crest is also desirable prior to the current zero during interruption under severe recovery voltage transient rates of rise. As well known by those skilled in the art, the interrupter can withstand a recovery voltage after interruption at least equal to the arc voltage prior to interruption. This feature is enhanced by this interrupter since the arc is lengthened suddenly by the cross-blast action prior to current zero, producing a spike 76 of arc voltage.

A puffer-type of gas-blast breaker will have an arcvoltage wave substantially as shown in FIG. 6 of the drawings, and an oil circuit interrupter will have an arc-voltage wave, as shown in FIGURE 7 of the drawings. Consequently, comparing the arc voltage of FIG. 8 with those of FIGS. 6 and 7, it will be readily apparent that a remarkable decrease in reduction of power dissipation is provided within the circuit interrupter 1 of the instant invention by the novel arc-extinguishing unit construction 62.

It will be noted that a distinct advantage is present in having the movable contact 42 serve as an orifice for gas flow. This results in immediate gas flow even before contact separation and in speeding up the interruption process. In addition, not only is there provided an axial flow of gas through the mouth '72 of the orifice contact 42, but also there is provided a cross-blast of gas, since the arc is drawn between the tip portion 53 of the arcing horn 5'7 and the inner side wall of the movable tubular contact 4-2. As a result, there is provided both a cross-blast action and an axial-flow blast action of the gas during the interruption operation.

FIGURE 5 illustrates the position of the several contact parts in the fully open-circuit position of the inter rupter 1. It will be observed that the relatively stationary contact fingers 69 are protected from corona formation by the surrounding electrostatic shield 70. As a result, voltage breakdown across the separated contact gap is not permitted to occur. The shield 70, in addition, serves as a spring seat for a plurality of circumferentially-disposed biasing compression spring 25, which assist the inherent resiliency of the fingers as in making contact with movable contact 42.

During the closing operation, the operating mechanism, disposed interiority within the housing 112, is effective to cause reciprocal motion of the operating shaft disposed within operating tube 15 and to effect leftward closing movement of the insulating operating rod 73. This will effect compression of the several accelerating compression springs 35 and will also bring the contact structure to its closed-circuit position as shown in FIG. 3.

From the foregoing description it will be apparent that there is provided an improved arc-extinguishing unit in which rapid arc transfer and highly efficient gas-flow conditions are encountered. The circuit-interrupting unit 62 of the present invention is particularly adaptable for a dual-pressure gas-flow type of circuit interrupter, in which the gas, which is employed, is preferably sulfurhexafiuoride (SP gas, sclenium-hexafiuoride (SeF gas (or mixtures of one or more of the aforesaid gases with carbon dioxide, air, helium, hydrogen, argon and nitrogen. However, although particularly outstanding results are achieved by use of one or more of the aforesaid gases, excellent performance is achieved by the use of other gases, for instance even compressed air. To indicate the outstanding performance of the circuit-interrupting unit 62 of the present invention, it is to be observed that such a contact and orifice structure interrupted 28,000 amperes in an arcing time of 0.7 cycle with a rate of rise corrected to a two-pole unit of 10,000 volts-permicrosecond. The gas flow through the tubular orifice contact 42 is not impeded since the total area of the slots 43, associated with the movable orifice contact 4-2, is equal to the cross-sectional area of the orfice opening 72 through the movable orifice contact 4-2. As a result, free exhausting of gas through the movable orifice contact 42 is provided during the opening operation. In addition, the travel of the movable contact 42 is superimposed upon the travel caused by gas flow exerted upon the moving terminal end of the arc 63a (FIG. 4-). In other words, the inner extremity 63a of the are 63 is lengthened not only by movement of the movable contact structure 42, but also by movement caused by the gas flow blasting through the mouth 72 of the movable orifice contact 42. This leads to extremely highly effective lengthening of the are as and consequent highlyefiective extinguishing action exerted thereon.

Unlike compressed air breakers which are likely to produce harmful overvoltages when interrupting transformer magnetizing currents as shown in FIG. 9, the unique construction of this interrupter limits any possible overvoltages to relatively low safe values. Since, as previously mentioned, the interrupting action begins immediately following contact part, interrupting effort is available at extremely small contact gaps.

In addition, although the moving contact is moving away from the finger contacts, 54, the actual gap lengthens initially to that between the inside of the moving contact, 4-2, and the arc horn, 57. Since the moving contact, 42, moves parallel to the arc horn, 57, the gap remains at approximately /8 inch until the tip of the moving contact, 42, clears the end of the arc horn. Therefore, a gap is drawn which remains very small for an appreciable period of time. The gas blast forces a premature current zero. As well known, this tends to produce high transient overvoltages on the system. On this interrupter, the recovery voltage is limited by the dielectric strength of the gap and a series of current reignitions and interruptions occurs (see FIG. 9). When an adequate withstand gap is obtained, the overvoltage-producing energy has been largely dissipated in the reignitions. The current has then been interrupted without producing overvoltages which could possibly harm the system. A saving of time of t as shown in FIG. 9, is obtained as compared to the performance of a compressed-air breaker.

Although there has been disclosed and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. A compressed-gas circuit interrupter including means at least partially of insulating material defining an interrupting chamber having an entrance opening therein, a relatively stationary contact disposed within the interrupting chamber, a movable tubular contact movable through said entrance opening into contacting engagement with the relatively stationary contact to complete the circuit through the circuit interrupter, means for admitting gas under pressure freely without obstruction into the interrupting chamber during the opening operation, venting means for said interrupting chamber provided through said movable tubular contact to cause gas fiow to take place interiorly of the movable tubular contact during the opening operation, and said venting means constituting the sole vent from the chamber during the interrupting process.

2. The combination in a gas-flow type of circuit interrupter of a cylindrical insulating member defining an interrupting chamber, a round inlet opening associated with one end of the cylindrical insulating member, a relatively stationary contact disposed within the interrupting chamber, a movable tubular contact movable through said inlet opening into contacting engagement with the relatively stationary contact to complete thecircuit through the circuit interrupter, means for admitting gas under pressure freely without obstruction into the interrupting chamber during the opening operation, venting means for said interrupting chamber provided through said movable tubular contact to effect gas flow interiorly of the movable tubular contact during the opening operation, and said venting means constituting the sole vent from the chamber during the interrupting process.

3. A compressed-gas circuit interrupter including means at least partially of insulating material defining an in terrupting chamber having an entrance opening therein, a relatively stationary contact disposed within the interrupting chamber, a movable tubular contact movable through said entrance opening into contacting engagement with the relatively stationary contact to complete the circuit through the circuit interrupter, said entrance opening making a relatively terrupting chamber provided through said movable tubular contact to cause gas flow to take place interiorly of the movable tubular contact during the opening opera tion, and said venting means constituting the sole vent from the chamber during the interrupting process.

4. The combination in a gas-flow type of circuit interrupter of a cylindrical insulating member defining an interrupting chamber, a round inlet opening associated with one end of the cylindrical insulating member, a relatively stationary contact disposed within the interrupting chamber, a movable tubular contact movable through said inlet opening into contacting engagement with the relatively stationary contact to complete the circuit through the circuit interrupter, said round inlet opening of the cylindrical insulating member making a relatively tight fit with the movable tubular contact, means for admitting gas under pressure freely without obstruction into the interrupting chamber during the opening operation, venting means for the interrupting chamber provided through said movable tubular contact to cause gas flow to take place interiorly of the movable tubular contact during the opening operation, and said venting means constituting the sole vent from the chamber during the interrupting process.

5. A compressed-gas circuit interrupter including means defining a pressure chamber, means for admitting gas under pressure freely without obstruction to said pressure chamber, said pressure chamber having an inlet opening for reception of a movable tubular contact, said movable tubular contact having a vent opening provided therethrough so that it functions as an orifice in addition to carrying current, a relatively stationary finger cluster disposed within the pressure chamber for bearing on the outside surface of the movable tubular contact, an arcing horn projecting within the interior of the tip portion of the movable tubular contact, the arc transferring from the relatively stationary fingers to the arc horn during the opening operation to prevent are erosion of the finger contacts, and the vent opening provided through the movable tubular contact constituting the sole vent for said pressure chamber during the interrupting process.

6. A compressed-gas circuit interrupter including means defining a pressure chamber, means for admitting gas under pressure freely without obstruction to said pressure chamber, said pressure chamber having an inlet opening for reception of a movable tubular contact, said movable tubular contact having a vent opening provided therethrough so that it functions as an orifice in addition to carrying current, said inlet opening making a relatively tight fit with said movable tubular contact to force gas fiow through the movable orifice contact, a relatively stationary finger cluster disposed within the pressure chamber for bearing on the outside surface of the movable tubular contact, an arcing horn projecting within the interior of the tip portion of the movable tubular contact, the arc transferring from the relatively stationary fingers to the are born during the opening operation to prevent arc erosion of the finger contacts, and the vent opening provided through the movable tubular contact constituting the sole vent for said pressure chamber during the interrupting process.

7. A compressed-gas circuit interrupter including means defining a pressure chamber, means for admitting gas under pressure freely without obstruction to said pressure chamber, said pressure chamber having an inlet opening for reception of a movable tubular contact, said movable tubular contact having a vent opening associated therewith so that it functions as an orifice in addition to carry current, a relatively stationary finger cluster disposed within the pressure chamber for bearing on the outside surface of the movable tubular contact, an arcing horn projecting within the interior of the tip portion of the movable tubular contact, the arc transferring from the relatively stationary fingers to the arc horn during the opening operation to prevent arc erosion of the finger contacts, said arcing horn being eccentric with respect to the center-line of the finger cluster to facilitate arc transfer, and the vent opening provided through the movable tubular contact constituting the sole vent for said pressure chamber during the interrupting process.

8. A compressed-gas circuit interrupter including means at least partially of insulating material defining an interrupting chamber having an entrance opening therein, a relatively stationary contact disposed within the interrupting chamber, a movable tubular contact movable through said entrance opening into contacting engage ment with the relatively stationary contact to complete the circuit through the circuit interrupter, means for admitting gas under pressure freely without obstruction into the interrupting chamber during the opening operation, venting means for said interrupting chamber provided through said movable tubular contact to efiect gas iiow interiorly of the movable tubular contact during the opening operation, a tubular metallic electrostatic guide shield at the same potential as the movable contact into which the movable contact is withdrawn, and said venting means constituting the sole vent from the chamber during the interrupting process.

9. An arc-extinguishing assemblage for a multi-break compressed-gas circuit interrupter including a plurality of spaced aligned interrupting units and a generally laddershaped movable contact assemblage, the movable contact assemblage including a pair of insulating operating rods and intervening cross-arms carrying tubular movable con tacts, each interrupting unit including a tubular cup-shaped insulating member having a restricted inlet opening therein, the several movable contacts being slotted so that gas flow may take place therethrough, relatively stationary contact structure with which each movable tubular contact may engage after passing through the restricted inlet opening during the closing operation, means for forcing a blast of compressed-gas freely without obstruction through each cup-shaped tubular insulating member of each interrupting unit during the opening operation, whereby each movable tubular contact transmits a flow of highpressure gas therethrough and functions as an orifice during the opening operation, and the vents through the 1OVflbl tubular contacts constituting the sole vents for the interrupting chambers during the interrupting process.

10. An arc-extinguishing assemblage for a multi-break compressed-gas circuit interrupter including a plurality of spaced aligned interrupting units and a generally ladtier-shaped movable contact assemblage, the movable contact assemblage including a pair of insulating operating rods and intervening cross-arms carrying tubular movable contacts, each interrupting unit including a tubular cup-shaped insulating member having a restricted inlet opening therein, the several movable contacts being slotted so that gas flow may take place therethrough, relatively stationary contact structure with which each movable tubular contact may engage after passing through the restricted inlet opening during the closing operation, means for forcing a blast of compressed-gas freely without obstruction through each cup-shaped tubular insulating member of each interrupting unit during the opening operation, whereby each movable tubular contact transmits a flow of high-pressure gas therethrough and functions as an orifice during the opening operation, each respective relatively stationary contact structure including an annular contact finger cluster and an interiorly located arc horn which projects into the tip of the respective movable tubular contact in the closed-circuit position, and the vents through the movable tubular contacts constituting the sole vents for the interrupting units during the interrupting process.

References Cited in the file of this patent FOREIGN PATENTS 359,295 Great Britain Oct 22, 1931 541,941 Great Britain Dec. 18, 1941 570,511 Great Britain July 10, 1945 87,834 Sweden Nov. 10, 1936 645,006 Germany May 20, 1937 

1. A COMPRESSED-GAS CIRCUIT INTERRUPTER INCLUDING MEANS AT LEAST PARTIALLY OF INSULATING MATERIAL DEFINING AN INTERRUPTING CHAMBER HAVING AN ENTRANCE OPENING THEREIN, A RELATIVELY STATIONARY CONTACT DISPOSED WITHIN THE INTERRUPTING CHAMBER, A MOVABLE TUBULAR CONTACT MOVABLE THROUGH SAID ENTRANCE OPENING INTO CONTACTING ENGAGEMENT WITH THE RELATIVELY STATIONARY CONTACT TO COMPLETE THE CIRCUIT THROUGH THE CIRCUIT INTERRUPTER, MEANS FOR ADMITTING GAS UNDER PRESSURE FREELY WITHOUT OBSTRUCTION INTO THE INTERRUPTING CHAMBER DURING THE OPENING OPERATION, VENTING MEANS FOR SAID INTERRUPTING CHAMBER PROVIDED THROUGH SAID MOVABLE TUBULAR CONTACT TO CAUSE GAS FLOW TO TAKE PLACE INTERIORLY OF THE MOVABLE TUBULAR CONTACT DURING THE OPENING OPERATION, AND SAID VENTING MEANS CONSTITUTING THE SOLE VENT FROM THE CHAMBER DURING THE INTERRUPTING PROCESS. 